Activation button assembly and injection needle insertion mechanism for injector

ABSTRACT

An injector includes an injection needle and an activation button assembly operatively connected to the injection needle. The activation button assembly is translatable from an unactuated position to an actuated position, the actuated position being visually different than the unactuated position. A position of the activation button assembly between the unactuated position thereof and the actuated position thereof defines a threshold point, and movement of the activation button assembly beyond the threshold point secures the activation button assembly in the actuated position, and drives the injection needle from a retracted position thereof to an injection position thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplication No. 62/543,753, titled “Tactile Button Feedback”, filed onAug. 10, 2017, the entire contents of which are incorporated byreference herein.

BACKGROUND OF THE DISCLOSURE

The present disclosure is generally directed to an injector, and, moreparticularly, to an activation button and an injection needle insertionmechanism of an injector.

An injector, such as, for example, a drug injector, is oftenself-operated by a user unfamiliar with the device. Accordingly, theuser may mishandle or improperly use the injector absent sufficientguidance and feedback. For example, a user may fail to properly activatethe injector if unsure of the status of the device, or may prematurelyinterrupt the injection process. A user may also be confused whetherthey properly actuated an activation button. Alternatively, a user maybe confused whether the device has been previously used or is still new.Such scenarios may result in improper use of the device, potentiallydangerous or wasteful premature removal of the device, unnecessarydisposal of the device, and/or at least anxiety on the part of the user.Moreover, improper activation of the injector may result in incompleteinjection needle deployment.

Therefore, it would be advantageous to manufacture an injector having anactivation button with both visual and tactile, e.g., haptic,differentiation between an unactuated state and a properly actuatedstate thereof to clearly and intuitively indicate proper activation tothe user. It would also be advantageous to manufacture an injectoremploying a needle insertion mechanism that is deployed solely uponproper activation of the device, thereby removing user induced error indeployment.

BRIEF SUMMARY OF THE DISCLOSURE

Briefly stated, one aspect of the present disclosure is directed to aninjector. The injector includes an injector housing, and an injectionneedle translatable along a needle axis between a retracted position,wherein at least a tip of the injection needle is contained within theinjector housing, and an injection position, wherein at least the tip ofthe injection needle protrudes from the injector housing. An activationbutton assembly is movably mounted to the injector housing andoperatively connected to the injection needle. The activation buttonassembly is translatable along a button axis, parallel to the needleaxis, from an unactuated position to an actuated position, the actuatedposition being visually different than the unactuated position. Abiasing member is connected with the activation button assembly and theinjection needle. The biasing member is stabilized in a stored energystate in the unactuated position of the activation button assembly, andreleased in the actuated position of the activation button assembly intoan energy releasing state to drive the injection needle along the needleaxis from the retracted position thereof to the injection positionthereof. A position of the activation button assembly between theunactuated position thereof and the actuated position thereof defines athreshold point, and movement of the activation button assembly beyondthe threshold point secures the activation button assembly in theactuated position.

Another aspect of the invention is directed to an injector. The injectorincludes an injector housing, and an injection needle translatable alonga needle axis between a retracted position, wherein at least a tip ofthe injection needle is contained within the injector housing, and aninjection position, wherein at least the tip of the injection needleprotrudes from the injector housing. An activation button assembly ismovably mounted to the injector housing and operatively connected to theinjection needle. The activation button assembly is translatable along abutton axis, parallel to the needle axis, from an unactuated position toan actuated position, the actuated position being visually differentthan the unactuated position. A biasing member is connected with theactivation button assembly and the injection needle. The biasing memberis stabilized in a stored energy state in the unactuated position of theactivation button assembly, and released in the actuated position of theactivation button assembly into an energy releasing state to drive theinjection needle along the needle axis from the retracted positionthereof to the injection position thereof. A position of the activationbutton assembly between the unactuated position thereof and the actuatedposition thereof defines a threshold point, and release of the biasingmember into the energy releasing state to drive the injection needlefrom the retracted position thereof to the injection position thereof istriggered solely upon movement of the activation button assembly beyondthe threshold point.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of aspects of the disclosure will bebetter understood when read in conjunction with the appended drawings.It should be understood, however, that the disclosure is not limited tothe precise arrangements and instrumentalities shown. In the drawings:

FIG. 1 is a top and front perspective view of a wearable injector, inaccordance with a first embodiment of the present disclosure;

FIG. 2 is an enlarged partial cross-sectional view of an activationbutton assembly and an injection needle insertion mechanism of theinjector of FIG. 1, taken along the sectional line 2-2 of FIG. 1, withthe activation button assembly in an unactuated position thereof and theinjection needle in a retracted position thereof;

FIG. 3 is an enlarged partial cross-sectional view of the activationbutton assembly and the injection needle insertion mechanism of theinjector of FIG. 1, taken along the sectional line 2-2 of FIG. 1, withthe activation button assembly moved toward an actuated position thereofand the injection needle in the retracted position thereof;

FIG. 4 is an enlarged partial cross-sectional view of the activationbutton assembly and the injection needle insertion mechanism of theinjector of FIG. 1, taken along the sectional line 2-2 of FIG. 1, withthe activation button assembly further moved toward the actuatedposition thereof and the injection needle in the retracted positionthereof;

FIG. 5 is an enlarged partial cross-sectional view of the activationbutton assembly and the injection needle insertion mechanism of theinjector of FIG. 1, taken along the sectional line 2-2 of FIG. 1, withthe activation button assembly in the actuated position thereof and theinjection needle in an injection position thereof;

FIG. 6 is an enlarged, partial cross-sectional view of the activationbutton assembly and the injection needle insertion mechanism inaccordance with a second embodiment of the present disclosure, takenalong the sectional line 2-2 of FIG. 1, with the activation buttonassembly in the unactuated position thereof and the injection needle inthe retracted position thereof; and

FIG. 7 is an enlarged, partial cross-sectional view of the activationbutton assembly and the injection needle insertion mechanism of FIG. 6,taken along the sectional line 2-2 of FIG. 1, with the activation buttonassembly in the actuated position thereof and the injection needle inthe injection position thereof.

DETAILED DESCRIPTION OF THE DISCLOSURE

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “lower,” “bottom,” “upper” and “top”designate directions in the drawings to which reference is made. Thewords “inwardly,” “outwardly,” “upwardly” and “downwardly” refer todirections toward and away from, respectively, the geometric center ofthe injector, and designated parts thereof, in accordance with thepresent disclosure. Unless specifically set forth herein, the terms “a,”“an” and “the” are not limited to one element, but instead should beread as meaning “at least one.” The terminology includes the words notedabove, derivatives thereof and words of similar import.

It should also be understood that the terms “about,” “approximately,”“generally,” “substantially” and like terms, used herein when referringto a dimension or characteristic of a component of the disclosure,indicate that the described dimension/characteristic is not a strictboundary or parameter and does not exclude minor variations therefromthat are functionally similar. At a minimum, such references thatinclude a numerical parameter would include variations that, usingmathematical and industrial principles accepted in the art (e.g.,rounding, measurement or other systematic errors, manufacturingtolerances, etc.), would not vary the least significant digit.

Referring to the drawings in detail, wherein like numerals indicate likeelements throughout, there is shown in FIGS. 1-5 an injector, generallydesignated 10, in accordance with a first embodiment of the presentdisclosure. In the illustrated embodiment, the injector 10 takes theform of a wearable injector (patch injector), such as, for example,without limitation, a wearable drug injector, but the disclosure is notso limited. As should be understood by those of ordinary skill in theart, the injector 10 generally includes a housing 12 having a firstsurface 14 configured to contact a skin surface of a user (not shown),e.g., a patient, the first surface 14 having an opening 14 a therein. Inthe illustrated embodiment, the first surface 14 defines a base surfaceof the injector housing 12, but the disclosure is not so limited. Thehousing 12 also includes a second surface 15 opposing the first surface14. In the illustrated embodiment, the second surface 15 defines a top,external surface of the injector housing 12, but the disclosure is notso limited.

As shown in FIGS. 2-5, a needle hub 16, constructed, for example, from apolymeric or metal material, combinations thereof, or the like, ismovably mounted within the injector housing 12 and an injection needle18 is supported by the movable needle hub 16 in a manner well understoodby those of ordinary skill in the art. In the illustrated embodiment,the needle hub 16 and the injection needle 18 are axially translatablealong a needle axis A (FIG. 2) extending substantially perpendicularlyto the first surface 14, between a retracted position (FIG. 2), whereinat least a tip 18 a of the injection needle 18 is contained within theinjector housing 12, and an injection position (FIG. 5), wherein atleast the tip 18 a of the injection needle 18 protrudes from theinjector housing 12 through the opening 14 a. As should be understood bythose of ordinary skill in the art, however, the axis A may bepositioned at angles other than 90° relative to the first surface 14. Asalso should be understood, the injection needle 18 may be movablymounted within the injector housing 12 via other mechanisms than theneedle hub 16.

A depressible activation button assembly 20, constructed, for example,from a polymeric or metal material, a combination thereof, or the like,is movably mounted to the injector housing 12 and operatively connectedto the injection needle 18 (as will be explained in further detail). Inthe illustrated embodiment, the activation button assembly 20 ispositioned within a cradle indent 15 a in the second surface 15 of theinjector housing 12, but the disclosure is not so limited. The cradleindent 15 a defines an opening in the second surface 15, through whichthe activation button assembly 20 extends into the interior of theinjector housing 12. The activation button assembly 20 is translatablealong a button axis B, parallel to the needle axis A, from an unactuatedposition (FIGS. 1, 2) to an actuated position (FIG. 5) (as will beexplained in further detail below). In the illustrated embodiment, theinjector housing 12 includes a securing post 12 a (shown best in FIGS.2, 5) projecting upwardly from the first surface 14 toward the secondsurface 15 along the button axis B. The securing post 12 a slidablyreceives a complementary translation post 20 a (shown best in FIGS. 2,5) projecting downwardly from the activation button assembly 20 alongthe button axis B. The translation post 20 a is configured, i.e., shapedand dimensioned, to matingly slide within the securing post 12 a duringtranslation of the activation button assembly 20 with respect to theinjector housing 12 to assist in stabilizing translation of theactivation button assembly 20 along the button axis B.

As shown in FIGS. 2-5, a biasing member 22 is operatively connected withthe activation button assembly 20 and the injection needle 18. Thebiasing member 22 is stabilized in a stored energy state in theunactuated position of the activation button assembly 20 (FIG. 2) andreleased in the actuated position (FIG. 5) of the activation buttonassembly 20 into an energy releasing state to drive the injection needle18 along the needle axis A from the retracted position thereof to theinjection position thereof. As should be understood by those of ordinaryskill in the art, the stored energy state of the biasing member 22 is astate in which the biasing member 22 stores at least some potentialenergy. The energy releasing state of the biasing member 22 is a stateof the biasing member 22 in which the biasing member 22 releases atleast some of the stored potential energy from the stored energy state.

In the illustrated embodiment, the biasing member 22 takes the form of acoil spring expandable from the energy storing state, in which thespring 22 is at least partially compressed, to the energy releasingstate, in which the spring 22 is expanded relative to the energy storingstate. As should be understood by those of ordinary skill in the art,however, the biasing member 22 may alternatively take the form of othermembers capable of storing and releasing energy. Non-limiting examplesinclude other springs (e.g., torsion or leaf springs), elastic bands,and the like. Alternatively, the biasing member 22 may take the form ofan actuator configured to apply a translational force onto the injectionneedle 18.

In the illustrated embodiment, the coil spring 22 is mounted between theneedle hub 16 and the activation button assembly 20, i.e., the spring 22abuts the activation button assembly 20 at one end and abuts the needlehub 16 at an opposing end. In the energy storing state thereof, thespring 22 applies a biasing force at the one end on the activationbutton assembly 20, biasing the activation button assembly 20 into theunactuated position thereof, and also applies an oppositely directedbiasing force at the other end on the needle hub 16.

As shown best in FIG. 2, the activation button assembly 20 defines anexternal surface 20 b, e.g., the top surface of the button assembly 20engageable by a user, and a plurality of angularly spaced members 20 cextending therefrom and forming respective hook shaped terminal ends 20d. The members 20 c may be integral, i.e., unitary and monolithic, withthe surface 20 b, but the disclosure is not so limited. The cradleindent 15 a, within which the activation button assembly 20 ispositioned, includes a flanged member 15 b extending downwardlytherefrom. In the unactuated position of the activation button assembly20 (FIG. 2), the hook shaped terminal ends 20 d of the members 20 cengage the flanged member 15 b under the biasing force of the spring 22,thereby maintaining the activation button assembly 20 in the unactuatedposition and preventing the activation button assembly 20 from beingremoved from the housing 12. As should be understood by those ofordinary skill in the art, however, the activation button assembly 20may be secured in the unactuated position thereof via other means,currently known or that later become known. In the unactuated position,the external surface 20 b of the activation button assembly 20 issubstantially flush with the second surface 15 of the injector housing12 (FIG. 2). As will be explained in further detail below, theactivation button assembly 20 is depressed within the cradle indent 15 ain the actuated position relative to the unactuated position (FIG. 5),e.g., the external surface 20 b is below the second surface 15 a. Asalso should be understood, however, the activation button assembly 20may alternatively be positioned differently relative to the injectorhousing 12 in the actuated and unactuated positions thereof, wherein theactuated position of the activation button assembly 20 remains visuallydifferent than the unactuated position thereof. For example, theactivation button assembly 20 may be elevated relative to the secondsurface 15 in the unactuated position thereof. Advantageously, thevisual and haptic differentiation between the activation button assembly20 positions serves as an intuitive, noticeable and continuousindication for the user that the injector has been successfullyactivated and remains activated.

The opposite end of the spring 22, as indicated previously, abuts theneedle hub 16 and applies a biasing force onto the needle hub 16directed toward the first surface 14, along the needle axis A. Thespring 22 is prevented from driving the needle hub 16 and the injectionneedle 18 into the injection position, however, until the activationbutton assembly 20 is moved into the actuated position, as will beexplained further below.

In the illustrated embodiment, as shown in FIGS. 2-4, the injector 10includes an elongate first post 24 connected with the injector housing12 and projecting upwardly therefrom, and a deflectable, second post 26connected with the injector housing 12 and projecting upwardlytherefrom. The first and second posts 24, 26 may be integral, i.e.,unitary and monolithic, with the injector housing 12, but the disclosureis not so limited. The first and second posts 24, 26 may also each beconstructed from a polymeric or metal material, combinations thereof, orthe like. In the illustrated embodiment, the first and second posts, 24,26 project upwardly from the first surface 14, but the disclosure isalso not so limited, and the first and second posts 24, 26 may projectfrom other portions of the injector housing 12. As shown best in FIGS.2-3, the second post 26 includes a flange 26 a projecting laterallytherefrom. In the illustrated embodiment, the flange 26 a projectslaterally from a terminal, upper end of the second post 26, but thedisclosure is not so limited. As should be understood, the flange 26 amay project laterally from others portions of the second post 26,provided that the flange 26 a is capable of performing the functionsdescribed herein. The flange 26 a supports a portion of the needle hub16 thereon, thereby securing the needle hub 16 and the injection needle18 in the retracted position thereof, i.e., obstructing the spring 22from driving the needle hub 16 and the injection needle 18 into theinjection position. In the illustrated embodiment, the needle hub 16includes a complementary laterally extending flange 16 a abutting theflange 26 a, but the disclosure is not so limited. As should beunderstood, however, others portions of the needle hub 16 may engage theflange 26 a, such as, for example, without limitation, an underside ofthe needle hub 16. Accordingly, engagement of the hook shaped terminalends 20 d of the members 20 c with the flanged member 15 b of the cradleindent 15 a at one end of the spring 22, and engagement of the flange 26a of the second post 26 with the flange 16 a of the needle hub 16maintain the spring 22 in an energy storing state, prior to movement ofthe activation button assembly 20 into the actuated position thereof.

The elongate first post 24 includes a terminal upper end defining aflange 28. The flange 28 includes an upper surface 28 a, defining theupper end of the first post 24, a lower surface 28 b projectinglaterally from the first post 24 further than a lateral extent of theupper surface 28 a, and a downwardly inclined surface 28 c from theupper surface 28 a to the lower surface 28 b. The lateral projection ofthe lower surface 28 b from the elongate post 24 defines an undercutunderlying the inclined surface 28 c. The inclined surface 28 c andlower surface 28 b, i.e., the undercut, of the elongate first post 24meet at a vertex 30.

The activation button assembly 20 includes a first arm 32 projectingdownwardly from the top surface 20 b. The first arm 32 may be integral,i.e., unitary and monolithic, with the top surface 20 b, but thedisclosure is not so limited. Alternatively, for example, the first arm32 may be attached to the activation button assembly 20 via otherattachment means currently known or that later become known. The firstarm 32 may also be constructed from a polymeric or metal material,combinations thereof, or the like. The first arm 32 includes a laterallyprojecting, flanged, terminal, lower end 32 a, forming a generallyhook-shaped end 32 a of the first arm 32. The flange 32 a is positionedopposite the downwardly inclined surface 28 c of the first post 24 inthe unactuated position of the activation button assembly 20. In oneembodiment, a lateral tip of the flange 32 a may define a complementaryincline to the inclined surface 28 c for smoother sliding thereon. Asshould be understood by those of ordinary skill in the art, the positionof the flange 28 along the first post 24 and the position of the flange32 a along the first arm 32 is not limited to the respective upper andlower ends of the first post 24 and the first arm 32, but rather may bemoved so long as the flange 32 a is positioned opposite the downwardlyinclined surface 28 c.

The first arm 32 is constructed to be more elastically flexible than theelongate first post 24, and the second post 26 is constructed to be moreelastically flexible than the first arm 32. That is, the first post 24is constructed to define a greater bending stiffness, i.e., resistanceagainst bending deformation, than the first arm 32, and the first arm 32is constructed to define a greater bending stiffness than the secondpost 26. Such properties may be achieved via relative materialproperties, between the first post 24, the first arm 32 and the secondpost 26, relative dimensions between the first post 24, the first arm 32and the second post 26, or a combination thereof

As shown in FIGS. 2-5, depression of the activation button assembly 20along the button axis B engages the flange 32 a of the first arm 32 withthe inclined surface 28 c of the first post 24 and slides the flange 32a down the inclined surface 28 c. As the first arm 32 is moreelastically flexible, i.e., deflectable, than the first post 24, slidingof the flange 32 a along the inclined surface 28 c elastically deflectsthe first arm 32 (FIGS. 3, 4) from an original state, e.g., undeflectedor less deflected, thereof (FIG. 2).

The vertex 30 defines a threshold point along the activation buttonassembly 20 pathway, and solely movement of the activation buttonassembly 20 beyond the vertex 30 secures the activation button assemblyin the actuated position thereof. That is, movement of the first arm 32of the activation button assembly 20 beyond the vertex 30 (FIG. 5)triggers retraction of the deflected first arm 32 back toward theoriginal state thereof, and the flanged terminal end 32 a thereofengages with the undercut 28 b of the elongate first post 24, e.g.,hooks or snaps back into engagement with the undercut 28 b, to securethe activation button assembly in the actuated position thereof.Alternatively, movement of the activation button assembly 20 that doesnot position the flange 32 a beyond the vertex 30 (e.g., FIG. 3) resultsin return of the activation button assembly 20 to the unactuatedposition thereof. That is, depression of the activation button assembly20 further compresses the spring 22 in the energy storing state thereof,thereby charging the spring 22 with additional potential energy, untilthe flange 32 a extends beyond the vertex 30. Accordingly, movement ofthe activation button assembly 20 that does not extend the flange 32 abeyond the vertex 30 results in the spring 22 driving the activationbutton assembly 20 back toward the unactuated position. Additionally, oralternatively, the elasticity of the deflected first arm 32 drives thefirst arm 32 back up the inclined surface 28 c to return to originalstate thereof, thereby returning the activation button assembly 20 tothe unactuated position thereof.

Movement of the flange 32 a of the first arm 32 beyond the vertex 30 ofthe first post 24, thereby triggering retraction of the deflected firstarm 32 back toward the original, e.g., undeflected or less deflected,state thereof allows the flange 32 a of the first arm 32 to engage withand deflect the second post 26 (due to the previously disclosed relativeproperties thereof) in the opposite direction. That is, the second post26 is positioned such that return of the first arm 32 toward theoriginal state thereof allows the first arm 32 to contact and deflectthe second post 26. Accordingly, deflection of the second post 26 movesthe flange 26 a of the deflected second post 26 away from the flange 16a of the needle hub 16, thereby releasing the needle hub 16, and, inturn, releasing the spring 22 into the energy releasing state to drivethe needle hub 16 and the injection needle 18 from the retractedposition thereof to the injection position thereof (FIG. 5). Thus,release of the spring 22 into the energy releasing state thereof istriggered upon movement of the first arm 32 of the activation buttonassembly 20 beyond the vertex 30, i.e., the threshold point.

Advantageously, therefore, insufficient user depression of theactivation button assembly 20 that does not move the first arm 32 of theactivation button assembly 20 beyond the threshold point 30 will merelyreturn the injector 20 into the original unused state thereof, withoutany negative affect on injection needle 18 deployment. Furtheradvantageously, once the first arm 32 moves beyond the threshold point,the injection needle 18 is driven into the injection position thereofunder the biasing force of the biasing member 22, irrespective of theforce utilized to depress the activation button assembly 20. Thus, adesired preset injection force of the injection needle 18 may beconfigured during injector manufacture, according to the biasing forceof the biasing member 22.

FIGS. 6-7 illustrate a second embodiment of the injector 110. Thereference numerals of the second embodiment are distinguishable fromthose of the above-described first embodiment (FIGS. 1-5) by a factor ofone-hundred (100), but otherwise indicate the same elements as indicatedabove, except as otherwise specified. The injector 110 of the presentembodiment is substantially similar to that of the earlier embodiment.Therefore, the description of certain similarities and modes ofoperation between the embodiments may be omitted herein for the sake ofbrevity and convenience, and, therefore, is not limiting.

One difference of the injector 110 over the embodiment of FIGS. 1-5,pertains to the configuration of the activation button assembly 120 andthe assembly of the biasing member 122. As shown in FIG. 6, the biasingmember, e.g., spring, 122 is mounted within the activation buttonassembly 120 in the stored energy state thereof, when the activationbutton assembly is in the unactuated position. The first arm 132 of theactivation button assembly 120 includes a lip 132 b laterally extendingtherefrom in a direction opposite the direction of the flange 132 a. Thespring 122 abuts the underside of the top surface 120 b of theactivation button assembly 120 at one end and engages the lip 132 b atthe opposing end when the actuation button assembly is in the unactuatedposition thereof.

The flange 132 a interacts with the elongate first post 124 in a similarmanner as described with respect to the embodiment of FIGS. 1-5. In theunactuated position of the activation button assembly 120 (FIG. 6), thelip 132 b catches the spring 122 and maintains the spring 122 in theenergy storing state. The flange 132 a is engaged with the inclinedsurface 128 c of the first post 124, slightly deflecting the first arm132 laterally in the direction of the lip 132 b. Depressing theactivation button assembly 120 slides the flange 132 a down the inclinedsurface 128 c of the post 124, further deflecting the first arm 132laterally in the direction of the lip 132 b, i.e., toward the spring122. Such deflection of the first arm 132 maintains the engagement ofthe spring 122 with the lip 132 b. Such deflection of the first arm 132(by depressing the activation button assembly 120) also stores potentialenergy in the first arm 132 to straighten back out, thereby sliding backup the inclined surface 128 c of the first post 124 and returning theactivation button assembly 120 to the unactuated position thereof if thefirst arm 132 does not travel past the threshold point.

Movement of the activation button assembly 120 sufficiently such thatthe flange 132 a of the first arm 132 surpasses the vertex 130, i.e.,the threshold point, triggers retraction of the deflected first arm 132back toward a substantially undeflected state thereof, hooking/snappingthe flanged terminal end 132 a thereof into engagement with the undercut128 b of the first post 124 and securing the activation button assembly120 in the actuated position thereof (FIG. 7). Retraction of thedeflected first arm 132 back toward a substantially undeflected statethereof, upon movement of the flange 132 a beyond the vertex 130, alsoengages the flange 132 a with the second post 126 and deflects thesecond post 126 to release the needle hub 116. Return of the first arm132 into a substantially undeflected configuration thereof also releasesthe lip 132 b from the spring 122. As shown in FIG. 7, the spring 122 isreleased into the energy releasing state to engage and drive thereleased needle hub 116 and the injection needle 118 from the retractedposition thereof to the injection position thereof

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. For example, without limitation, a cam ordetent mechanism may alternatively be utilized with the activationbutton assembly to define a threshold point along the pathway thereof,rather than the inclined surface. Likewise, for example, various needledriving mechanisms may be implemented, such an electrical switchactivated needle driving mechanism. It is understood, therefore, thatthis disclosure is not limited to the particular embodiments disclosed,but it is intended to cover modifications within the spirit and scope ofthe present disclosure, as set forth in the appended claims.

1. A wearable injector comprising: an injector housing comprising a basesurface and an opposing top surface, the base surface being configuredto contact a skin surface of a user and having an opening therein, andthe top surface defining an opening therethrough; an injection needlemounted within the injector housing and translatable along a needle axisbetween a retracted position, wherein at least a tip of the injectionneedle is contained within the injector housing, and an injectionposition, wherein at least the tip of the injection needle protrudesfrom the injector housing through the opening in the base surface; andan activation button assembly movably mounted to the injector housingand operatively connected to the injection needle, the activation buttonassembly being translatable along a button axis, parallel to the needleaxis, from an unactuated position to an actuated position, an externalsurface of the activation button assembly being depressed below the topsurface of the injector housing in the actuated position; and a biasingmember connected with the activation button assembly and the injectionneedle, the biasing member being stabilized in a stored energy state inthe unactuated position of the activation button assembly, and releasedin the actuated position of the activation button assembly into anenergy releasing state to drive the injection needle along the needleaxis from the retracted position thereof to the injection positionthereof, wherein: a position of the activation button assembly betweenthe unactuated position thereof and the actuated position thereofdefines a threshold point, in the stored energy state, the biasingmember biases the activation button assembly into the unactuatedposition thereof and returns the activation button assembly to theunactuated position in response to movement of the activation buttonassembly short of the threshold point; and movement of the activationbutton assembly beyond the threshold point secures the activation buttonassembly in the depressed actuated position.
 2. The injector of claim 1,wherein the activation button assembly is depressible along the buttonaxis, and wherein the activation button assembly is depressed in theactuated position relative to the unactuated position.
 3. The injectorof claim 1, wherein a top surface of the activation button assembly isgenerally flush with an external surface of the injector housing in theunactuated position of the activation button, and wherein the activationbutton assembly is secured in a position in the actuated positionthereof wherein the top surface of the actuation button assembly isdepressed from the external surface of the injector housing.
 4. Theinjector of claim 1, wherein the biasing member biases the activationbutton assembly into the unactuated position thereof.
 5. The injector ofclaim 4, wherein the biasing member returns the activation buttonassembly to the unactuated position thereof in response to movement ofthe activation button assembly not surpassing the threshold point. 6.The injector of claim 1, wherein release of the biasing member into theenergy releasing state to drive the injection needle from the retractedposition thereof to the injection position thereof is triggered solelyupon movement of the activation button assembly beyond the thresholdpoint.
 7. The injector of claim 6, further comprising a needle hubmovably mounted within the injector housing, the injection needle beingsupported by the movable needle hub and the needle hub and the injectionneedle being translatable between the retracted position and theinjection position.
 8. The injector of claim 7, wherein the biasingmember comprises a spring connected at one end with the activationbutton assembly and connected at an opposing end with the needle hub,the spring being compressed into an at least partially contractedconfiguration in the stored energy state.
 9. The injector of claim 7,further comprising: an elongate first post connected with the injectorhousing and projecting upwardly therefrom, the elongate first posthaving an upper end comprising a downwardly inclined surface and anundercut underlying the inclined surface; and the activation buttonassembly comprises a downwardly projecting first arm having a flangedterminal end slidable along the inclined surface of the elongate firstpost, the first arm being elastically deflectable from an original statethereof, wherein movement of the activation button assembly along thebutton axis slides the flanged terminal end of the first arm along theinclined surface of the first post, thereby elastically deflecting thefirst arm away from the original state thereof.
 10. The injector ofclaim 9, wherein the inclined surface and the undercut of the elongatefirst post meet at a vertex defining the threshold point.
 11. Theinjector of claim 10, wherein movement of the activation button assemblybeyond the vertex triggers retraction of the first arm back toward theoriginal state thereof, hooking the flanged terminal end thereof ontothe undercut of the elongate first post and securing the activationbutton assembly in the actuated position thereof.
 12. The injector ofclaim 11, further comprising a deflectable second post connected withthe injector housing and projecting upwardly therefrom, the deflectablesecond post including a flange supporting a portion of the needle hubthereon, thereby securing the needle hub and the injection needle in theretracted position thereof.
 13. The injector of claim 12, wherein themovement of the activation button beyond the vertex, triggeringretraction of the first arm back toward the original state thereof,engages the flanged terminal end of the first arm with the second postand deflects the second post, whereby the deflected second post releasesthe needle hub, and, in turn, releases the biasing member into theenergy releasing state to drive the needle hub and the injection needlefrom the retracted position thereof to the injection position thereof14. A wearable injector comprising: an injector housing comprising abase surface and an opposing top surface, the base surface beingconfigured to contact a skin surface of a user and having an openingtherein, and the top surface defining an opening therethrough; aninjection needle mounted within the injector housing and translatablealong a needle axis between a retracted position, wherein at least a tipof the injection needle is contained within the injector housing, and aninjection position, wherein at least the tip of the injection needleprotrudes from the injector housing through the opening in the basesurface; and an activation button assembly movably mounted to theinjector housing and operatively connected to the injection needle, theactivation button assembly being translatable along a button axis,parallel to the needle axis, from an unactuated position to an actuatedposition, an external surface of the activation button assembly beingdepressed below the top surface of the injector housing in the actuatedposition; and a biasing member connected with the activation buttonassembly and the injection needle, the biasing member being stabilizedin a stored energy state in the unactuated position of the activationbutton assembly, and released in the actuated position of the activationbutton assembly into an energy releasing state to drive the injectionneedle along the needle axis from the retracted position thereof to theinjection position thereof, wherein: a position of the activation buttonassembly between the unactuated position thereof and the actuatedposition thereof defines a threshold point, in the stored energy state,the biasing member biases the activation button assembly into theunactuated position thereof and returns the activation button assemblyto the unactuated position in response to movement of the activationbutton assembly short of the threshold point, and release of the biasingmember into the energy releasing state to drive the injection needlefrom the retracted position thereof to the injection position thereof istriggered solely upon movement of the activation button assembly beyondthe threshold point.